An ongoing argument in the defining and assessment of farm animal welfare has been over what criteria should and should not be used. The authors constructed a computerized welfare assessment model for gestating sows, called the SOWWEL (from SOw WELfare), based on a hierarchical organization of the sows’ needs. The model was constructed using data from previous scientific studies. The housing and management systems are inputted into the model and it will generate an overall welfare score. Thirty-seven attributes associated with welfare related properties of the housing and management system are found within the model (ie: space per pen, health status, feeding levela